干法合成阳离子淀粉的研究

讨论了干法制备阳离子淀粉工艺中阳离子试剂、催化剂用量及反应温度、反应时间等因素对取代度和反应效率的影响。研究表明最佳工艺条件是:淀粉、醚化剂及NaOH加入量的质量比为50∶18∶5,淀粉含水量为34%,反应温度60℃,时间5h,可以制备出取代度为0.289,反应效率为75%的高取代度阳离子淀粉。     

微波辅助干法制备阳离子木薯淀粉

采用微波辅助加热法干法制备阳离子淀粉,详细考察了微波功率、微波辐照时间、氢氧化钠用量和3-氯-2-羟丙基三甲基氯化铵醚化剂(CHPTMA)用量等对反应效率及其产品取代度的影响。结果表明:微波干法合成阳离子淀粉,反应时间短,反应效率高;在NaOH分2次加入、NaOH与淀粉质量比为4.0%、醚化剂用量为淀粉质量的4.5%、水用量为淀粉用量的25.0%、微波功率为450 W及微波辐照时间为3.0 min等条件下,阳离子淀粉取代度为0.037 5,阳离子醚化剂反应效率高达93.76%。     

高取代度阳离子淀粉的制备方法研究

用玉米淀粉与3-氯-2-羟丙基三甲基氯化铵(CHPTMA)为原料,通过常温干法和高温干法制备高取代度季铵型阳离子淀粉醚。研究了水的用量、氢氧化钠用量、醚化剂用量、反应温度和反应时间对取代度和反应效率的影响。当淀粉用量为100g、CHPTMA用量为0.345mol、氢氧化钠用量为0.375mol、反应温度80℃、反应时间2.5h时为最佳反应条件,此时,取代度为0.445,反应效率为79.6%。     

高取代度阳离子淀粉—丙烯酰胺接枝共聚物的制备及应用

以高取代度的阳离子淀粉为原料,硝酸铈铵为引发剂,制备了高取代度阳离子淀粉—丙烯酰胺接枝共聚物,研究了丙烯酰胺与阳离子淀粉质量比、反应温度、反应时间、引发剂浓度对接枝率和接枝效率的影响。结果表明:接枝率和接枝效率最高的条件为丙烯酰胺与阳离子淀粉质量比2.5∶1,反应温度55℃,反应时间3h,引发剂浓度2.5mmol/L。将合成的聚合物用于废水处理,高取代度阳离子淀粉—丙烯酰胺接枝共聚物的用量为4mg/L对麦草浆中段废水的处理效果最好,废水CODcr去除率为34.1%,浊度的去除率为13.5%。     

高取代度阳离子淀粉的制备与应用

通过干法制备高取代度阳离子淀粉 ,原料是玉米淀粉和土豆淀粉。用甲醇把淀粉润湿后加入三口烧瓶 ,再加入适量的醚化剂。用w =40 %的NaOH溶液调pH值为 8～ 9。温度控制在 60～ 70℃ ,连续加热搅拌 4h。反应后的产物经过抽滤后自然干燥得粉状产品。通过化学分析 ,证明所得产品为高取代度阳离子淀粉 ,并对增干强性能进行了检测。阳离子玉米淀粉和阳离子土豆淀粉都能比较明显地提高纸张的干强度 ,当用量为w =1 %时 ,增干强度分别提高2 1 .0 %和 1 8.4%。     

干混法制备阳离子淀粉工艺方法研究

用醚化剂GTA与玉米淀粉在不加碱或只加催化量碱的情况下,进行反应以制备低取代度阳离子淀粉,研究了反应温度、反应时间、体系pH值、体系含水量、GTA用量对取代度、反应效率的影响.在不加碱的情况下,当淀粉的用量9.6g,GTA的用量0.4g,反应时间3h,温度控制在50℃,制得低取代度阳离子淀粉.所得的产物的取代度为0.037 9,反应效率为85.2%.其他条件不变,体系中加入2.5 mL pH值为9的水溶液,所得的阳离子淀粉的取代度为0.038 7,反应效率为86.8%.     

阳离子淀粉作为表面施胶剂的研究

本文的研究目的是为了满足市场对增加纸张内部和表面强度,改善印刷性能和提高纸张强度的需求,采用将木薯淀粉阳离子化原纸进行表面施胶,然后测定纸张性能,探讨阳离子淀粉作为表面施胶剂的最佳应用条件。本文探讨了阳离子淀粉用作纸张表面施胶剂的作用机理,初步研究了制备阳离子淀粉的最优化条件,不同取代度的阳离子淀粉作为表面施胶剂的应用效果。通过对纸张性能（抗张强度、环压强度、吸水性）的测定,找出阳离子淀粉应用的优点。实验结果表明制备阳离子淀粉的最优化条件为木薯淀粉用量为50g,阳离子醚化剂用量为3.008g,n（NaOH）：n（CTA）=1.2：1,反应时间为2h,反应温度为40℃;阳离子淀粉作为表面施胶剂的最佳取代度和固含量分别为0.056和40%。     

醚化剂GTA的合成及其在干法制备阳离子淀粉中的应用

用环氧氯丙烷与三甲胺反应合成失水甘油基三甲基氯化铵 (GTA) ,研究了环氧氯丙烷的用量、反应介质对GTA收率的影响 ,然后将其与淀粉混合制备低、高取代度季铵型阳离子淀粉 ,研究了反应温度、反应时间、碱用量对取代度、反应效率的影响。     

半干法制备阳离子淀粉的工艺优化

以玉米淀粉为原料,3-氯-2-羟丙基三甲基氯化铵(CTA)为醚化剂,在碱性条件下,采用半干法制备低取代度阳离子淀粉。采用Box-Behnken中心组合响应面设计,对半干法工艺进行优化,并分析反应温度、反应时间、碱的用量、体系含水量对阳离子淀粉取代度的影响。结果表明:回归方程能较好地预测取代度随工艺条件变化的规律,半干法制备低取代度阳离子淀粉工艺条件为:反应温度64.40℃,反应时间6.58 h,NaOH与醚化剂摩尔比2.12,体系含水量25.28%,在此条件下制得的阳离子淀粉取代度为0.051 9。     

磷酸酯阳离子两性淀粉印染废水处理剂的合成及应用

以低取代度磷酸酯淀粉与阳离子醚化剂为原料,合成了一种新型两性磷酸酯阳离子淀粉印染废水处理剂。通过考察醚化反应体系p H、反应时间、反应温度及醚化剂用量对阳离子取代度的影响,确定了最佳反应条件为:反应体系p H=11,反应温度40℃,反应时间6 h。并测试了不同阳离子取代度磷酸酯阳离子两性淀粉水处理剂对印染废水的色度去除率,结果表明,阴离子取代度0.036 8、阳离子取代度0.013 1的磷酸酯阳离子两性淀粉脱色效果最好。     

Reliable identification of grapevine rootstock varieties using RAPD PCR on woody samples

Since grapevine ( Vitis spp .) rootstock material is being traded increasingly as disbudded woody material a lack of distinctive morphological features on such material necessitates an alternative and reliable means of identification. Methods described here were developed for rapid and efficient extraction of DNA from woody samples rich in phenolic compounds and polysaccharides, and for subsequent identification of varieties by RAPD PCR. Using these methods, and with the application of only one selected RAPD primer, we were able to differentiate sixteen rootstock varieties, including the seven varieties most commonly used in Germany. Problems commonly encountered with reproducibility of RAPD patterns were avoided by choosing primers with a dinucleotide sequence and a high G/C content that allowed a rather high annealing temperature of 45°C. Methods described here should also be useful for other horticultural crops, especially those with woody tissues rich in phenolic compounds and polysaccharides.     

An internet compendium of analytical methods and spectroscopic information for monomers and additives used in food packaging plastics

An internet website (http://cpf.jrc.it/smt/) has been produced as a means of dissemination of methods of analysis and supporting spectroscopic information on monomers and additives used for food contact materials (principally packaging). The site which is aimed primarily at assisting food control laboratories in the European Union contains analytical information on monomers, starting substances and additives used in the manufacture of plastics materials. A searchable index is provided giving PM and CAS numbers for each of 255 substances. For each substance a data sheet gives regulatory information, chemical structures, physico-chemical information and background information on the use of the substance in particular plastics, and the food packaging applications. For monomers and starting substances (155 compounds) the infra-red and mass spectra are provided, and for additives (100 compounds); additionally proton NMR are available for about 50% of the entries. Where analytical methods have been developed for determining these substances as residual amounts in plastics or as trace amounts in food simulants these methods are also on the website. All information is provided in portable document file (PDF) format which means that high quality copies can be readily printed, using freely available Adobe Acrobat Reader software. The website will in future be maintained and up-dated by the European Commission's Joint Research Centre (JRC) as new substances are authorized for use by the European Commission (DG-ENTR formerly DGIII). Where analytical laboratories (food control or other) require reference substances these can be obtained free-ofcharge from a reference collection housed at the JRC and maintained in conjunction with this website compendium.     

Aroma characterization of various apricot varieties using headspace–solid phase microextraction combined with gas chromatography–mass spectrometry and gas chromatography–olfactometry

The characterization of the aromatic profile of several apricot cultivars with molecular tracers in order to obtain objective data concerning the aromatic quality of this fruit was undertaken using headspace–solid phase microextraction (HS–SPME). Six apricot cultivars were selected according to their organoleptic characteristics: Iranien, Orangered, Goldrich, Hargrand, Rouge du Roussillon and A4025. The aromatic intensity of these varieties measured by HS–SPME–Olfactometry were defined and classified according to the presence and the intensity of grassy, fruity and apricot like notes. In the six varieties, 23 common volatile compounds were identified by HS–SPME–GC–MS. Finally, 10 compounds, ethyl acetate, hexyl acetate, limonene, β-cyclocitral, γ-decalactone, 6-methyl-5-hepten-2-one, linalool, β-ionone, menthone and (E)-hexen-2-al were recognized by HS–SPME–GC–O as responsible of the aromatic notes involved in apricot aroma and considered as molecular tracers of apricot aromatic quality which could be utilized to discriminate apricot varieties.     

Tests of potential functional barriers for laminated multilayer food packages. Part I: Low molecular weight permeants

The advent of the functional barrier concept in food packaging has brought with it a requirement for fast tests of permeation through potential barrier materials. In such tests it would be convenient for both foodstuffs and materials below the functional barrier (sub-barrier materials) to be represented by standard simulants. By means of inverse gas chromatography, liquid paraffin spiked with appropriate permeants was considered as a potential simulant of sub-barrier materials based on polypropylene (PP) or similar polyolefins. Experiments were performed to characterize the kinetics of the permeation of low molecular weight model permeants (octene, toluene and isopropanol) from liquid paraffin, through a surrogate potential functional barrier (25 μm-thick oriented PP) into the food simulants olive oil and 3% (w/v) acetic acid. These permeation results were interpreted in terms of three permeation kinetic models regarding the solubility of a particular model permeant in the post-barrier medium (i.e. the food simulant). The results obtained justify the development and evaluation of liquid sub-barrier simulants that would allow flexible yet rigorous testing of new laminated multilayer packaging materials.     

Chlorohydrins of bisphenol A diglycidyl ether (BADGE) and of bisphenol F diglycidyl ether (BFDGE) in canned foods and ready-to-drink coffees from the Japanese market

BADGE.2HCl and BFDGE.2HCl were determined in 28 samples of ready-to-drink canned coffee and 18 samples of canned vegetables (10 corn, 5 tomatoes and 3 others), all from the Japanese market. HPLC was used as the principal analytical method and GCMS for confirmation of relevant LC fractions. BADGE.2HCl was found to be present in one canned coffee and five samples of corn, BFDGE.2HCl in four samples of canned tomatoes and in one canned corn. No sample was found which exceeded the 1mg/kg limit of the EU for the BADGE chlorohydrins. However the highest concentration was found for the sum of BFDGE.2HCl and BFDGE.HCl.H₂O at a level of 1.5mg/kg. A Beilstein test confirmed that all cans containing foods contaminated with BADGE.2HCl or BFDGE.2HCl had at lest one part coated with a PVC organosol.     

European priorities for research to support legislation in the area of food contact materials and articles

A strong science base is required to underpin the planning and decision-making process involved in determining future European community legislation on materials and articles in contact with food. Significant progress has been made in the past 5 years in European funded work in this area, with many developments contributing to a much better understanding of the migration process, and better and simpler approaches to food control. In this paper this progress is reviewed against previously identified work-areas (identified in 1994) and conclusions are reached about future requirements for R&D to support legislation on food contact materials and articles over the next 5 or so years.     

Analysis of benzo[a]pyrene in spiked fatty foods by second derivative synchronous spectrofluorimetry after microwave-assisted treatment of samples

A simple, rapid and inexpensive method has been developed for the determination of benzo[a     

The development of reference materials for paralytic shellfish poisoning toxins in lyophilized mussel. II: Certification study

This paper describes the second part of a project undertaken to develop certified mussel reference materials for paralytic shellfish poisoning toxins. In the first part two interlaboratory studies were undertaken to investigate the performance of the analytical methodology for several PSP toxins, in particular saxitoxin and decarbamoyl-saxitoxin in lyophilized mussels, and to set criteria for the acceptance of results to be applied during the certification exercise. Fifteen laboratories participated in this certification study and were asked to measure saxitoxin and decarbamoyl-saxitoxin in rehydrated lyophilized mussel material and in a saxitoxin-enriched mussel material. The participants were allowed to use a method of their choice but with an extraction procedure to be strictly followed. The study included extra experiments to verify the detection limits for both saxitoxin and decarbamoyl-saxitoxin. Most participants (13 of 15) were able to meet all the criteria set for the certification study. Results for saxitoxin.2HCl yielded a certified mass fraction of <0.07 mg/kg in the rehydrated lyophilized mussels. Results obtained for decarbamoyl-saxitoxin.2HCl yielded a certified mass fraction of 1.59+/-0.20 mg/kg. The results for saxitoxin.2HCl in enriched blank mussel yielded a certified mass fraction of 0.48 +/- 0.06 mg/kg. These certified reference materials for paralytic shellfish poisoning toxins in lyophilized mussel material are the first available for laboratories to test their method for accuracy and performance.     

Announcing a new international peer-reviewed journal:Food Science and Human Wellness now accepting manuscript submission in English

<正>We are pleased to announce the launch of a new international peer-reviewed journal-Food Science and Human Wellness,ISSN 2213-4530,which is an open access journal,produced and hosted by Elsevier B.V.on behalf of Beijing Academy of Food Sciences.Food Science and Human Wellness is an international peer-reviewed English journal that provides a forum for the dissemination of the